1. Field of the Invention
The present invention relates to a recording system for recording image data transmitted from a host computer using a recording apparatus. More specifically, the present invention relates to a recording system including an ink-jet recording apparatus having a plurality of interfaces.
The recording apparatus of the present invention is applicable to any apparatus dealing with recording media, e.g., pieces of paper, cloth, leather, non-woven fabrics, overhead projector (OHP) sheets, recording media made of metal, etc. More specifically, the recording apparatus of the present invention may be implemented as an office machine, such as a printer, a copying machine, or a facsimile machine, an industrial production machine, or the like.
2. Description of the Related Art
With the recent popularity of personal computers, word processors, facsimile machines, etc., in the office or at home, a variety of printers having different recording methods have been developed as information output apparatuses for these devices. Ink-jet printers are suitable for business use in the office and for personal use at home because of their advantages, that is, easy color recording, low noise during operation, high-quality recording onto multiple recording media, compactness, etc. In particular, ink-jet recording apparatuses of the serial-scan type (hereinafter referred to as “recording apparatuses”) in which a recording head is reciprocated so as to scan on a recording medium to perform recording can record images with high quality at low cost, and therefore have become widely used.
With the prevalence of recording apparatuses, a greater number of interfaces for connecting the recording apparatuses to host computers have become available. Interfaces include wire and wireless interfaces, namely, serial communication interfaces, parallel communication interfaces, and infrared communication interfaces. For example, a recording apparatus having a plurality of interfaces is disclosed in Japanese Patent Laid-Open No. 2000-280582.
With the ability of recording apparatuses to print high-resolution, high-quality images, multiple color images, etc., the capacity of image data has increased. With the high processing rate of printer engines, a large amount of image data has also been increasingly handled.
A host computer that transfers image data to a recording apparatus includes a plurality of interfaces having different transfer rates for a wide variety of applications, such as a USB (Universal Serial Bus) interface and a BT (Bluetooth) interface. The differences in the transfer rates cause a problem when image data is transferred from the host computer to the recording apparatus. For example, when a large amount of image data is transferred from the host computer via a high-rate interface, e.g., a USB 2.0 interface, the difference between the time required for transferring the image data and the time required for recording the image data is small and is therefore negligible.
However, when a large amount of image data is transferred via a low-rate interface, such as a BT interface, the time required for transferring the image data is longer than the time required for recording the image data, and therefore the performance of the printer engine cannot be fully utilized. In this case, a data queuing problem occurs in which the printer waits for the image data to be transferred and therefore the time required for recording becomes long.
The data queuing problem increases the number of nozzle recovery (preliminary ejection) procedures, which are performed at predetermined time intervals for maintaining high performance of ink ejection, and also increases the amount of wasted ink.
The ink-jet recording apparatus may also have other problems. When ink is applied to adjacent pixels, time differences for applying ink to the individual pixels cause differences in penetration of the ink into the recording medium. Large time differences cause color variations in a recorded image. Data queuing causes the recording intervals (scan intervals) to randomly change, and an output image is therefore susceptible to color variations.
When an amount of image data that is reduced by reducing the number of grayscale levels is transferred from a host computer to a recording apparatus via a low-transfer-rate interface, the image quality is greatly reduced although the occurrence of data queuing is avoidable. Even when such image data is transferred via a high-rate interface, which does not cause a data queuing problem, the image quality is also degraded.
One method to overcome these problems is to transfer data that is compressed with a high compression ratio from a host computer to a recording apparatus. Generally, it takes a longer time to decompress high-ratio compressed data than low-ratio compressed data. Therefore, when data compressed with a high compression ratio is transferred from a host computer to a recording apparatus, the recording apparatus requires a long time to decompress the compressed data, and must wait for the data to be decompressed. Thus, data queuing may also occur.
Typically, data to be transferred from a host computer to a recording apparatus is compressed with a low compression ratio, which does not cause data queuing due to the decompression time. A compression method using a low compression rate does not cause data queuing, and is therefore useful if there is no fear that data queuing occurs due to the communication rate.
Therefore, it is not desirable that data transferred from a host computer to a recording apparatus be compressed with a high compression ratio regardless of the communication rate.